What is Claws Mail?

Claws Mail is an e-mail client (& news reader) based on GTK+, running on the X Window System, and aiming for

Quick response

Graceful, and sophisticated interface

Easy configuration, intuitive operation

Abundant features

Extensibility

Robustness and stability

What are the differences between Claws Mail and Sylpheed?

Claws Mail (formerly Sylpheed-Claws) started as the bleeding-edge version of Sylpheed, in order to act as a testbed for new features for Sylpheed. The idea was to regularly resync with Hiroyuki's main branch, and vice-versa. Claws Mail then evolved into the stable extended version of Sylpheed, and is now an entity in its own right, mainly due to different goals and the fact that syncing both codebases doesn't happen anymore.

Claws Mail has many extra features compared to Sylpheed and is more powerful, yet is just as fast, lightweight and stable.

Where can I get Claws Mail?

Who writes Claws Mail?

How does Claws Mail store mails?

Mails are stored in the MH mailfile format as used by MH and EMH. Maildir and mbox format are supported via two plugins available on the Plugins page.

Does Claws Mail have mail filtering?

Yes. You can find it in Configuration->Filtering... tab.

Can Claws Mail handle local unix mailboxes?

Yes.

Can Claws Mail handle IPv6?

Yes, IPv6 is fully supported in Claws Mail.

How many POP3, News or IMAP accounts can I set up in Claws Mail?

The number is unlimited. The limit is reached when your computer stops responding.

Can I set up an Account for sending Mail only?

Yes, set up a new account using Configuration -> Create new Account and set the Protocol to None (SMTP only).
Or create a local Account for a MH-directory and disable automatic checking for new mail on that account.

How does Claws Mail check for MIME types?

Does Claws Mail allow me to write HTML styled messages?

No. A discussion has gone around over this topic, and the outcome was that HTML mail is not wanted. If you really need to send HTML, you can of course attach a webpage to an e-mail.

Does Claws Mail have name completion in the address fields?

Yes. When you search for a name that starts with "don", type "don" (without the quotes) and press the TAB key. This will show you the correct name (when only one "don" exists in your addressbook. Otherwise a dropdown list appears, which allows you to select the name you want. E.g. Donald Duck, Don Johnson. But also e-mail addresses starting with "don" will appear in the list (like "don.giovanni@maffia.org").

Why is Claws Mail so fast?

That's what it is designed for!

How can I send in patches, report bugs, talk about Claws Mail with others?

Can I import an mbox into Claws Mail's MH mailfolders?

Yes, just create/select the folder you want your mails in, and select "Import mbox file" in the File menu.

Can I use procmail to sort my mails with the MH mail handling?

Yes. Just make sure that you add /. to the end of a rule so procmail knows that you are filtering into an MH mail folder. Example :

0:
* ^Subject:.*claws
clawsmail/.

Check man procmail for details.

When I upgrade Claws Mail, are there things I should be aware of?

Yes, some more critical than others.

You should always read the RELEASE_NOTES document that is included in the release tarballs.
The release notes can also be viewed on the Claws Mail News page.

How can I quickly update the views in Claws Mail?

Just press Alt-U or select "update" from the summary menu.

Why does Claws Mail allow me to open more than one instance at the same time for the same user on a network?

Claws Mail opens a Unix-domain socket using a name constucted from your TMPDIR path plus your UID.
This socket is used to arbitrate multiple instances on a given machine.
In Linux, at least, named Unix-domain sockets are known only locally, to the creating machine.
Pointing your TMPDIR environment variable to /home/yours/tmp doesn't have the desired effect,
as the socket definition would need to be propagated across the LAN and isn't.

Does Claws Mail support Return Receipts?

Yes.

To request a Return Receipt use '/Options/Request Return Receipt' in the Compose window.

When you receive a message that requests a Return Receipt a notification area is shown just above the message view. You can either use the 'Send receipt' button, or ignore the request - no receipts are sent automatically.

You can choose to never send Return Receipts by using the option on the Mail Handling/Sending page of the Preferences. When you use this option, all Return Receipt requests are ignored and you will not be prompted to send one.

Why does Claws Mail load big folders slowly?

Certain options, although handy, can slow down Claws Mail. Consider disabling the following options to achieve more speed:
/Display/Summaries 'Display sender using address book'
/Display/Summaries 'Thread using subject in addition to standard headers'
/Plugins/GPG 'Automatically check signatures'
In the Message List, Sort by Date or other non-string headers instead of Subject, From or To.
Avoid using cpu intensive folder Processing rules conditions such as "Whole message", "Body part", etc, and Pre/Post processing.

How do I make a new Icon Theme for Claws Mail?

Obviously you need to have some artistic abilities (well, not much unless you want to make a really cool theme), but, apart from that, there's some technical points you should consider when making a new theme and you want to share it with the rest of the world:

Choose a license for it. Remember that themes without license are not free.

If you're using some other theme or graphic element you found on the web be careful and check its license also. Some authors use strange licenses which does not allow derivations or redistributions, or impose the original license over derived works.

If you're making original artwork and do not know (or care) which license to choose, GPL is a good and recommended option. It's the same license that Claws Mail uses.

Try to provide a full set of icons. The easiest way to do that is to copy all Claws Mail icons and start editing them.

Keep the sizes uniform. Claws Mail default icons are certain size, and some variations are allowed, but size disparity can not be a good idea if two icons are going to be displayed side to side.